An antenna system is a most vital part in a mobile radio communications system. Errors in the antenna system give rise to a reduced coverage area and a decrease in the information throughput. Hence, it is important to monitor the state of the antenna system.
One method of monitoring the state of an antenna system is to perform Voltage Standing Wave Ratio (VSWR) measurements, where a transmitted signal and the reflected part of the transmitted signal are determined and compared in order to determine the state of the antenna system. However, this method can only be used for the monitoring of antenna systems in radio base stations which comprise both a transmitter and a receiver.
Another method of monitoring antenna systems is to measure the DC feeder resistance. However, since the feeder resistance varies as equipment, such as filters, amplifiers etc., are introduced to or removed from, the antenna system, this method requires knowledge of which equipment is presently connected to the antenna system.
The above mentioned methods do not explicitly show whether the receiver is affected, but rather that the impedance of the antenna system has changed. A further problem with the above mentioned methods is that manual configuration of the measurement equipment is generally required, since there exist many different types of antenna configurations and transceiver/receiver units.